The spine is subject to various pathologies that compromise its load bearing and support capabilities. Such pathologies of the spine include, for example, degenerative diseases, the effects of tumors, and fractures and dislocations attributable to physical trauma. In the treatment of diseases, malformations or injuries affecting one or more spinal motion segments (which include two or more adjacent vertebrae and the disc tissue or disc space therebetween), and especially those affecting disc tissue, removal of some or all of a degenerated, ruptured or otherwise failing disc is sometimes required. It is also known that artificial discs, fusion implants, or other interbody devices can be placed into the disc space subsequent to removal of disc material. External stabilization of the spinal motion segments, alone or in combination with interbody devices, may be accomplished via attachment of one or more elongate plates, rods or other external stabilization devices to the spinal column.
Additionally, current operative methods for treating spinal deformities, particularly scoliosis, include correction of the spinal curvature via some form of internal fixation device, and fusion of the spine in the corrected state may be accomplished by the placement of bone graft between the adjacent vertebrae. Several instrumentation systems are available to correct and stabilize the spinal column while fusion occurs. Nonoperative methods also exist and may be used when applicable. These nonoperative methods include, for example, bracing and observation.
Patients with infantile or juvenile scoliosis who undergo curve stabilization via the use of subcutaneous rods are subject to multiple surgical procedures for lengthening and adjustment as they grow. As should be appreciated, it is generally preferable that the number of surgical procedures required for treatment of the spinal column be minimized. Additionally, anterior or posterior spinal fusion in a skeletally immature patient often results in loss of vertebral body height and girth. Another problem that sometimes arises is that some children are not physically able to tolerate the surgical procedures required for a definitive fusion procedure. Further, poor self-image may occur in adolescent patients who are externally braced for scoliosis. Moreover, curve stabilization with bracing is only successful in approximately 75% of patients.
While prior spinal stabilization and support systems are a step in the right direction, there remains room for additional improvements. For example, subsequent to implantation of prior stabilization systems, additional surgeries are sometimes required in order to adjust one or more components associated with the spinal construct. This is particularly true in instances involving growing patients, especially patients under the age of 10 years old, where the spinal construct must be periodically lengthened to accommodate for continued growth of the spinal column (e.g., to compensate for an increase in the distance between the spinal motion segments). In some instances, adjustments may be required every six months, thereby requiring multiple surgeries throughout the treatment process.
Thus, there is a general need in the industry to provided improved systems, devices and methods for stabilizing a portion of the spinal column using one or more elongate members. There is also a need to provide improved systems, devices and methods that reduce the number and/or frequency of adjustments to accommodate for continued growth of the patient's spinal column, particularly in pediatric patients having an immature spine. The present invention satisfies these and other needs and provides other benefits and advantages in a novel and unobvious manner.